Practical Demonstrations of Ergonomic Principles

RI 9684REPORT OF INVESTIGATIONS2011

Practical Demonstrations of

Ergonomic Principles

Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Report of Investigations 9684

Practical Demonstrations of Ergonomic Principles

Susan M Moore PhD Janet Torma-Krajewski PhD CIH CPE

Lisa J Steiner MS CPE

DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for D isease Control and Prevention

National Institute for Occupational Safety and Health Pittsburgh Research Laboratory

Pittsburgh PA

July 2011

This document is in the public domain and may be freely copied or reprinted

Disclaimer

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Occupational Safety and Health (NIOSH) In addition citations to Web sites external to NIOSH

do not constitute NIOSH endorsement of the sponsoring organizations or their programs or

products Furthermore NIOSH is not responsible for the content of these Web sites

The findings and conclusions in this report are those of the author(s) and do not necessarily

represent the views of the National Institute for Occupational Safety and Health

Ordering information

To receive documents or other information about occupational safety and health topics contact

NIOSH at

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DHHS (NIOSH) Publication No 2011-191

July 2011

SAFER bull HEALTHIER bull PEOPLEtrade

ii

CONTENTS

ACKNOWLEDGEMENTS v GLOSSARY vi SECTION 1 Introduction 1 Target Users and Audiences 1 Format of Demonstration Descriptions 2 Suggested Supplies 2 Graphics 3 SECTION 2 Neutral Postures 4 Principles 19 SECTION 4 Hand-Tool Selection and Use 28 Principles 28 SECTION 5 Fatigue Failure and Back Pain 37 Principles 37 SECTION 6 Moment Arms and Lifting 41 Principles 41 APPENDIX A Suggested Supplies 47 APPENDIX B Useful Images for Handouts 52 REFERENCES 56

iii

FIGURES

Figure 1 Neutral and awkward wrist postures 5 Figure 2 Neutral and awkward elbow postures 6 Figure 3 Neutral and awkward shoulder postures 6 Figure 4 Neutral and awkward back postures 7 Figure 5 Example of a portable EMG device (showing electrodes on skin) that indicates

muscle activity by emitting audible signals 8 Figure 6 Wrist postures and electrode placement for portable EMG device 9 Figure 7 Negative flat and positive tilt positions for a keyboard 10 Figure 8 Electrode placement on the upper arm 11 Figure 9 Electrode placement for the shoulder 12 Figure 10 Neutral abducted and flexed (reaching) shoulder postures 13 Figure 11 Electrode placement for the back (line indicates location of spine) I t is important

that the electrodes are placed on the muscles as shown in the photograph If the electrodes are placed too high on the back the demonstration will not work properly 14

Figure 12 Neutral moderately flexed and highly flexed postures of the back 15 Figure 13 Hand dynamometer showing how wrist angle affects force production for neutral

ulnar deviation and radial deviation wrist postures 18 Figure 14 Pinch (lateral) grip and power grip 20 Figure 15 Example of the maximum forces generated for a pinch grip ( lateral) and a power grip 22 Figure 16 Example of a pinch grip (lateral) and the resulting maximum force 24 Figure 17 The power grip i s shown for five different grip w idths The narrowest grip i s

Grip 1 the width increases for each subsequent grip with Grip 5 being the widest grip 26 Figure 18 Maximumndashforce output for each grip width Note that for this participant Grip 2

had the highest force production 27 Figure 19 Evaluating the effect of tool-handle diameter 30 Figure 20 Examples of situations in which a pistol grip and inline grip w ould be useful as a

means for keeping the wrist in a neutral posture32 Figure 21 Two types of pliers one with a spring that reduces forceful exertion when opening

the jaw and one without a spring 34 Figure 22 Example of one-handed and two-handed drilling 36 Figure 23 Image of vertebrae disc and endplates 37 Figure 24 A pe n cap that is bent multiple times visually shows fatigue a paper clip shows the

result of failure The graph (generalized for bone) illustrates how the same load lifted many times may ultimately over time lead to failure 40

Figure 25 These schematics illustrate how increasing the distance between the worker and the object being lifted increases the overall moment (ie torque) for which the back muscles must compensate by expending more force 42

Figure 26 A moment-arm simulator showing that more forceweight (W arrow indicates direction of force) is needed to balance the ldquosee sawrdquo if the moment arm (L) is shorter on one side of the fulcrum as compared to the other side 44

Figure 27 Moment-arm simulator with dial scale showing that as the moment arm is increased the resulting force acting on the scale increases 46

Figure A-1 Dimensions for the moment-arm simulator 49 Figure A-2 Examples of the suggested supplies for the demonstrations51

iv

ACKNOWLEDGEMENTS

The technical contributions of Dr Sean Gallagher pertaining to methods and materials used

for the demonstrations and his assistance writing the background for the lower back

demonstrations (Section 5) are acknowledged Additionally the assistance of Jonisha Pollard and

Mary Ellen Nelson in obtaining photographs of the demonstrations and the artistic work of

Alexis Wickwire are also acknowledged The authors also appreciate Alan Maytonrsquos and Patrick

McElhinneyrsquos willingness to participate in the demonstrations video Videotaping and editing of

the videos were professionally completed by Charles Urban

v

GLOSSARY

Awkward posture Deviation from the natural or ―neutral position of a body part A neutral

position places minimal stress on the body part Awkward postures typically include reaching

overhead or behind the head twisting at the waist bending the torso forward backward or to the

side squatting kneeling and bending the wrist

Cumulative injury (overuse injury) Cumulative injuries develop from repeated loading of

body tissues over time Such injuries include overuse sprainsstrains herniated discs tendonitis

and carpal tunnel syndrome

Disorder A medical condition that occurs when a body part fails to function properly

Ergonomics The science of fitting workplace conditions and job demands to the capabilities of

workers and designing and arranging items in the workplace for efficiency and safety

Fatigue failure The weakening or breakdown of material subjected to stress especially a

repeated series of stresses

Force The amount of physical effort a person uses to perform a task

Inline grip A hand tool with a straight handle that is parallel with the direction of the applied

energy

Moment (torque) The tendency to produce motion about an axis

Moment arm The perpendicular distance between an applied force and the axis of rotation For

muscles this is the perpendicular distance between the line of action of the muscle and the center

of rotation at the joint

Musculoskeletal disorders (MSDs) Illnesses and injuries that affect one or more parts of the

soft tissue and bones in the body The parts of the musculoskeletal system are bones muscles

tendons ligaments cartilage and their associated nerves and blood vessels

Neutral body posture The resting position of body parts

Pinch grip A grasp in which one presses the thumb against the fingers of the hand and does not

involve the palm

Pistol grip A tool handle that resembles the handle of a pistol and is typically used when the

tool axis must be elevated and horizontal or below waist height and vertical

Power grip A grasp where the hand wraps completely around a handle with the handle running

parallel to the knuckles and protruding on either side

vi

Repetitive Performing the same motions repeatedly over time The severity of risk depends on

the frequency of repetition speed of the movement number of muscle groups involved and

required force

Risk factor An action andor condition that may cause an injury or illness or make an existing

injury or illness worse Examples related to ergonomics include forceful exertion awkward

posture and repetitive motion

Stress Demand (or ―burden) on the human body caused by something outside of the body such

as a work task the physical environment work-rest schedules and social relationships

Traumatic injury Injuries that are acute that may result from instantaneous events such as

being struck by objects and that often require immediate medical attention These types of

injuries are often sustained through accidents

vii

SECTION 1 INTRODUCTION

Musculoskeletal disorders (MSDs) often involve the back wrist elbow andor shoulder

and occur when workers are exposed over time to MSD risk factors such as awkward postures

forceful exertions or repetitive motions These exposures sometimes occur due to poorly

designed workstations tasks andor hand tools [Chaffin et al 2006 Sanders and McCormick

1993 Silverstein et al 1996 1997] Workers must understand the nature of MSD risk factors

and how to avoid exposure to them In a classroom setting trainers may discuss ergonomic

principles and show examples of MSD risk factors with photographs or videos However

supplementing training with practical hands-on demonstrations may further reinforce these

ergonomic principles and help workers understand the importance of avoiding exposure to MSD

risk factors Moreover demonstrations that allow for worker participation result in a greater

understanding of the impact exposures to particular MSD risk factors have on workersrsquo bodies

This document consists of a series of demonstrations designed to complement training on

ergonomic principles A description of the materials needed and step-by-step methodology are

included in this document Each demonstration highlights worker participation and uses

relatively inexpensive materials

The demonstrations are organized by type of ergonomic principle Five general topics are

addressed

Neutral compared with non-neutral postures

Grip types

Hand-tool selection and use

Fatigue failure and back pain

Moment arms and lifting

The demonstrations show the effects of posture work methods workstation design tools

tasks and location of materials on worker exposure to MSD risk factors Many of the

demonstrations are appropriate supplements to the NIOSH-developed training ―Ergonomics and

Risk Factor Awareness Training for Miners which is provided to mining employees and

downloadable from the NIOSH mining website

httpwwwcdcgovnioshminingpubspubreferenceoutputid2748htm [NIOSH 2008]

Target Users and Audiences

This document was developed for individuals who intend to provide training on ergonomic

principles that focus on MSD risk-factor exposures It was designed for trainers of all

experience levels including the beginning trainer The demonstrations are designed to be

performed by both the trainer and the worker Each demonstration reinforces specific ergonomic

principles and teaches the worker how and why to avoid MSD risk factors Additionally

individuals involved in the purchase and selection of new andor replacement tools may benefit

from many of the demonstrations because they highlight the importance of considering

ergonomic principles before purchasing tools

Format of Demonstration Descriptions

Each section of this document begins with a discussion of an ergonomic principle and its

role in avoiding MSD risk factors followed by a series of demonstrations that may be used to

show how the principle can be incorporated into the work environment Each demonstration

starts with clear objective statements and concludes with take-home messages that participants

should incorporate into their everyday thinking These demonstrations encourage audience

participation because discussing how the principle plays a role in a workerrsquos specific workplace

is important for promoting understanding Each demonstration includes the following

information

Objectives of the demonstration

List of suggested supplies needed to conduct the demonstration

Step-by-step demonstration methodology

Take-home messages that should be emphasized during the demonstration

To assist the trainer in knowing how to use some of the suggested supplies (eg portable

EMG device hand dynamometer) a series of brief video clips on DVD are included with this

document The DVD also contains video clips that show how to perform the demonstration and

the results you should receive when using the portable electromyography (EMG) device

Suggested Supplies

A complete list of required supplies for performing the demonstrations is provided in

Appendix A As previously mentioned each demonstration description includes a list of

supplies specific to that demonstration Most of the supplies are available at hardware stores for

a reasonable cost

A portable EMG device is recommended for use with several of the demonstrations (Please

see Appendix A for more information regarding the purchase of this device including cost and

potential manufacturers) An EMG device is a rudimentary instrument that can be used to make

relative comparisons of muscle activity by measuring the electrical activity of a muscle The

muscle emits an electrical signal when it undergoes one of two types of contractionsmdash

concentric (ie when the muscle shortens as it contracts) or eccentric (ie when the muscle

lengthens as it contracts) When a contraction of the muscle is detected the device emits an

audible signal of beeps the frequency of these beeps increases as the measured activity of the

muscles beneath the electrodes increases For example if you place the electrodes on the inside

of the forearm and ask the participant to contract the forearm muscles to 50 of their maximal

effort you will hear the device beep at a specific frequency If you then ask the participant to

contract his or her forearms to a maximal level the frequency of the beeps will increase

One problem with measuring muscle activity using electrodes placed on the skin is that the

electrodes may measure what is referred to as ―crosstalk Crosstalk is produced when an

electrode measures a signal over a nonactive or nearby muscle For example if you apply the

electrodes to the inside of the forearm of the participant and have the participant flex his or her

wrist (ie move the palm towards the inside of the forearm) the forearm muscles being

measured are contracting and the EMG device will emit the audible signal However if you

have the participant extend his or her wrist (ie move the palm as far away from the inside of

the forearm as they can) the EMG device will still emit an audible signal even though the

2

muscles the electrodes reside above are not contracting This is an example of crosstalk where

the electrodes are detecting activity from the muscles on the other side of the forearm The

electrodes could also be detecting a small eccentric contraction if the participant is using the

inner forearm muscles to control the rate at which the wrist is extended If the trainer is not

aware of these issues the trainer and the participants may be confused by the seemingly

mistaken readings The trainer should practice the demonstrations provided in this document

prior to attempting them in front of an audience to minimize any occurrences where this

―crosstalk could cause confusion for the audience members

Another limitation in using electrodes is that the amount of electrical activity produced by

the different muscles of the body varies Therefore the EMG device provides the user with the

ability to select from several different scales You may need to adjust the scale in order for the

device to be sensitive enough to detect changes in muscle activity for your muscles of interest

You must use the same scale the entire time you are measuring the electrical activity of a

specific muscle group otherwise you will not be able to make a direct comparison to the

muscle activity before and after an event

Graphics

Appendix B includes several images that may be useful to show in a PowerPoint

presentation when conducting the demonstrations Electronic files for these graphics are found

on the DVD provided with this document

3

SECTION 2 NEUTRAL POSTURES

Principles

Use neutral postures

o Maximum muscle force producible in neutral postures is greater than maximum muscle force producible in awkward postures

o Fatigue occurs sooner when working in awkward postures

o Working in extreme awkward postures (near extreme

ranges of motion) causes stress on muscles and joints

A neutral posture is achieved when the muscles are at their resting length and the joint is

naturally aligned For most joints the neutral posture is associated with the midrange of motion

for that joint When a joint is not in its neutral posture its muscles and tendons are either

contracted or elongated Joints in neutral postures have maximum control and force production

[Basmajian and De Luca 1985 Chaffin et al 2006] Neutral postures also minimize the stress

applied to muscles tendons nerves and bones A posture is considered ―awkward when it

moves away from the neutral posture toward the extremes in range of motion

For the most part a worker is capable of producing his or her highest amount of force when

a joint is in its neutral posture As the joint moves away from the neutral posture the amount of

force the muscles can produce decreases because some of the muscle fibers are either contracted

or elongated [Clarke 1966 Kumar 2004] Also when you bend your wrist the tendons of the

muscles partially wrap around the carpal bones in the wrist Because the bones do not act as a

perfect pulley a loss in the force that can be produced will occur Furthermore losses in force

are also experienced due to friction [Ozkaya and Nordin 1999] Thus in order for a worker to

produce the same force in an awkward posture as they do in the neutral posture the workerrsquos

muscles must work harder and expend more energy Working in an awkward posture therefore

is a MSD risk factor that should be avoided This is an extremely important principle because

working closer to onersquos maximum capability especially without rest may result in an earlier

onset of fatigue and over time may also increase the risk of MSDs [Chaffin et al 2006]

Ideally tasks and workspaces should be designed so that work is conducted at approximately

15 or less of maximum capacity [Chaffin et al 2006]

Therefore to minimize the level of effort as a percentage of the maximum capacity you

should help workers use the neutral posture of their joints However some joint motion must

occur because remaining in a static posture for too long produces several negative consequences

and should be avoided When a worker remains in a static posture the prolonged application of

a load by the muscles can result in fatigue Also not moving muscles for a time impedes blood

4

flow which is needed to bring oxygen and crucial nutrients to the muscles and to remove

metabolic waste products Static postures are avoided when work is dynamic with the muscles

and joints periodically moving With this in mind workstations tasks and hand tools should be

designed to enable workers to use primarily neutral postures and postures that are in relative

proximity to the neutral posture Care should be taken to ensure that awkward postures are not

frequent and that high forces are not required while in awkward postures Figures 1ndash4 show

neutral and awkward postures for the joints (eg wrist elbow shoulder and back)

Figure 1 Neutral and awkward wrist postures

These

topics will be discussed in more detail in this document

Special considerations are made for the back and hand Even though the neutral posture of

the back technically occurs with the back slightly forward flexed lifting in a flexed posture can

place unwanted forces on the spine itself Lifting tasks should be performed while the back is

not flexed and the nonflexed posture is often called the neutral posture of the back The neutral

posture for the hand is achieved when the fingers are in a slightly flexed (relaxed) position

[Bechtol 1954]

5

Figure 2 Neutral and awkward elbow postures

Figure 3 Neutral and awkward shoulder postures

6

Figure 4 Neutral and awkward back postures

The following demonstrations are designed to highlight the effect that awkward postures

have on muscle activity for the wrist elbow shoulder and lower back

7

Effects of Postures on Muscle Activity

Objectives

To understand the

effect of neutral and

awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies

Portable EMG device indicating muscle activity via audible

sound (Figure 5)

Figure 5 Example of a portable EMG device (showing electrodes on skin) that indicates muscle activity by emitting

audible signals

Step-by-Step Demonstration Method (Wrist) See

Introduction video for EMG placement see

WristFlexionExtension video

1 Place the electrodes on the forearm (see supplemental

video clips for more information on electrode

placement)

2 Instruct participant to place his or her wrist in the

neutral posture and then extend the wrist until it is fully

extended and it is clear that the wrist is in an awkward

posture (Figure 6)

3 Note that the frequency and volume of the sounds

produced by the portable EMG device increase as the

joint moves away from the neutral posture and extends

into an awkward posture (indicating more muscle

activity)

Neutral Compared with Awkward Postures

8

4

5


Ask the audience to identify tasks at their worksite where they use extended wrist

postures or other awkward postures of the wrist (excessive flexion extension and

radialulnar deviations)

Discuss with the audience whether it would be possible to use a neutral posture to

perform these tasks If not ask the audience why they are limited to awkward postures

Identify changes to workstation design tasks tools or location of materials that may

allow neutral postures to be used

Figure 6 Wrist postures and electrode placement for portable EMG device


9


NOTE This demonstration can be used to train workers who use keyboards because it

focuses on evaluating wrist posture with the keyboard placed at different positions

including flat positive and negative tilt (Figure 7)

Figure 7 Negative flat and positive tilt positions for a keyboard


10


Step-by-Step Demonstration Method (Elbow) See BicepCurl video

1 Place the electrodes on the upper arm (Figure 8)

2 Instruct the participant to assume an elbow posture with a 90deg angle (neutral)

(Figure 8)

3 Note the intensity of the sounds from the portable EMG device

4 Instruct the participant to raise the forearm so that the elbow angle is less than

90deg (flexion) As the elbow angle is decreased the intensity of the sounds from

the portable EMG device will increase (indicating more muscle activity)

5 Ask the audience to identify tasks that require them to use awkward postures for

the elbow and how these postures might be avoided

Figure 8 Electrode placement on the upper arm


11


Step-by-Step Demonstration Method (Shoulder) See ShoulderRaise and

ShoulderReach videos

1 Place the electrodes on the shoulder (Figure 9)

2 Instruct the participant to assume a neutral shoulder posture (Figure 10)


4 Instruct the participant to raise his or her arm (abduction) so that it is parallel to

the ground As the shoulder angle is increased the intensity of the sounds from


5 Instruct the participant to reach above their head as if to change a light bulb As

the shoulder angle is increased further the intensity of the sounds from the

portable EMG device will also increase (indicating more muscle activity)


the shoulder and how these postures might be avoided

Figure 9 Electrode placement for the shoulder


12


Figure 10 Neutral abducted and flexed (reaching) shoulder postures


13

Effects of Postures on Muscle Activity Step-by-Step Demonstration Method (Low Back) See BackFlexionNoWeight

video

1 Place the electrodes on the low back (Figure 11)

2 Instruct the participant to slowly lean forward with the back at about a 45degndash60deg

angle and note the increase in the intensity of the sounds from the portable EMG

device (Figure 12) The muscle group being tested is referred to as the erector

spinae which undergoes an eccentric contraction as the trunk flexes forward

The erector spinae helps control the rate at which the torso is lowered by acting

against the abdominal muscles that are performing a concentric contraction to

flex the trunk However make sure the participant does not flex until their torso

is fully horizontal since the erector spinae is not as active once the torso comes to

rest The decreased activity as indicated by a decrease in audible EMG signals

may be confusing to the audience Before performing this demonstration in front

of a group practice determining the position of the torso when the activity of the

erector spinae diminishes This will help you to advise the participant to avoid

going beyond this position Although muscle activity has decreased at postures

near full flexion the spine continues to be loaded in an undesirable manner

Figure 11 Electrode placement for the back (line indicates location of spine) It is important that the electrodes are placed on the muscles as shown in the photograph If

the electrodes are placed too high on the back the demonstration will not work properly


14

Effects of Postures on Muscle Activity Take -Home Messages

Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue

3 Ask the participant to slowly return to a standing

position During this motion the erector spinae are

undergoing a concentric contraction in order to raise

the weight of the torso upward against the force of

gravity However when the participant is back in an

upright posture this activity will diminish as will the

frequency of the audible signal from the EMG device

4 Ask the audience to identify tasks at their worksite that

require them to work with their backs in flexed

postures and how these postures might be avoided

Figure 12 Neutral moderately flexed and highly flexed postures of the back


15

Wrist Angle and Grip Strength

Objectives

To increase

awareness of how

posture affects force

production

capabilities and

worker fatigue

To discuss tasks that

require workers to

use awkward

postures while

exerting force

Supplies

Hand dynamometer (Figure 13)

Stopwatch

Step-by-Step Demonstration Method See PowerGrip

video

1 Place the hand dynamometer in the participantrsquos hand and make sure hisher hand is in the neutral posture as

shown in Figure 13

2 Instruct the participant to squeeze with maximum

force and record the force heshe was able to produce

3 Instruct the participant to rotate his or her wrist into a

position of radial deviation (awkward posture)


force and record the force he or she was able to

produce The force should be less than the force

obtained with the wrist in the neutral posture


position of ulnar deviation (awkward posture see

Figure 13) Some people may not have sufficient range

of motion to move their wrist into this posture Before

performing this demonstration determine if the

participant selected for the demonstration can achieve

this posture



The force should be less than that produced with the

wrist in the neutral posture

7 Ask a few more audience members to participate The

trend will be the same for all participants even though

the maximum forces they can produce will vary


16


8 Now ask each participant to exert a force of 20 lbs while in the neutral posture

and hold that force as long as possible Record the length of time the participant

maintains the posture Then ask the participants to do the same using wr ist

positions with radial and ulnar deviations because fatigue occurs sooner in these

postures the length of time the force can be maintained for these postures should

be less than the time the force can be maintained using a neutral posture

9 Ask the audience to identify tasks at their worksite where awkward postures of

the wrist occur

NOTE Dramatic results will also be seen if this demonstration is performed with the

wrist in extension or flexion as shown in Figure 1


17

Wrist Angle and Grip Strength Take -Home Messages

When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture

instead of a neutral

posture

Figure 13 Hand dynamometer showing how wrist angle affects force production for neutral ulnar deviation and radial

deviation wrist postures


18

GSECTION 3 GRIP TYPES

Principles

Force generated with a pinch grip is about 15ndash25 of force generated with a power grip

Use a power grip when higher forces are required

Use a pinch grip when precise movements are needed and the force required is low (lt 2 lbs)

Research shows the design width of power grips should be 175 to 375 inches

In general an object can be grasped using one of two methods a pinch grip or a power grip

(Figure 14) A power grip curls the fingers toward the palm a pinch grip presses the thumb

against the fingers of the hand or an object and does not involve the palm The amount of force

that can be generated depends on the type of grip and the width of the grip

Three types of pinch grips can be used

Tip pinchmdashusing only the tips of the fingers and thumb (holding a bead)

Chuck pinchmdashusing the thumb and first two fingers (holding a pencil)

Lateral pinchmdashusing the thumb and side of the first finger (holding a key)

For a given force using a pinch grip is biomechanically more stressful than using a power

grip The amount of force one is capable of exerting is greater for the power grip than for the

pinch grip A general rule of thumb is that the force generated with a pinch grip is about 15ndash

25 of the force generated with a power grip depending on the type of pinch grip and the

workerrsquos individual force capability The amount of force exerted also varies among the three

types of pinch grips When using a tip pinch the force exerted is 71ndash72 of the lateral pinch

force when using a chuck pinch the force exerted is 98 of the lateral pinch force The amount

of force generated by power grips and pinch grips also varies depending on the width of the

grip For a power grip the maximum force is generated with a grip width of 175ndash375 inches

For a pinch grip (type not specified by citation) the maximum force is generated with a grip

width of 1ndash3 inches [Chengalur et al 2004]

19

A pinch grip provides more control because the thumb joint is highly movable and precise

In contrast minimal control is associated with the power grip as the fingers move as one entity

and only in one direction (flexion) For these reasons pinch grips are typically used for short-

duration low-force and precision tasks because they require minimal force exertion but high

control (eg tightening or removing eyeglass screws) In general tasks that are done repeatedly

and require 2 lbs or more of force should not involve pinch grips For example tasks that

require using a power drill are ideally suited to the use of a power grip because the neutral

posture for the fingers is a slightly flexed position [NIOSH 2004]

Figure 14 Pinch (lateral) grip and power grip

NOTE Grip type is greatly influenced by hand-tool design Therefore a separate section in

this document (see Section 4) has been devoted to hand-tool selection and use and follows this

section on grip types

20

Power Grip Compared with Pinch Grip

Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies

Hand dynamometer that measures pinch-grip strength

(Figure 15)

Hand dynamometer that measures power-grip strength

(Figure 15)

Step-by-Step Demonstration Method See

LateralPinchGrip TipPinchGrip ChuckPinchGrip and

PowerGrip videos

1 Place dynamometer for pinch grip measurements

between the participantrsquos thumb and forefinger as

shown in Figure 15 (lateral)

2 Instruct the participant to exert maximum force

3 Note the maximum force produced

4 Place the dynamometer for power-grip measurements

in the palm of participantrsquos hand as shown in Figure

15



7 Ask several participants to exert maximum forces using

both pinch (lateral tip and chuck) and power grips

Record these results

8 Discuss the differences between the maximum forces

generated for the different types of grips

9 Discuss the differences among individuals in

generating forces using all types of grips

Grip Types

21


Take -Home Messages

A pinch grip should

be used only for

precision tasks that

require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not

require high degrees

of precision and

dexterity

10 Discuss specific tasks that would be appropriate for

using either type of grip

11 Identify specific tasks the worker performs that uses

the different types of grips and determine if the grip is

appropriate for the task requirements

Figure 15 Example of the maximum forces generated for a pinch grip (lateral) and a power grip

Grip Types

22

Pinch Grip Strength and Applications

Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies

Hand dynamometers that measures pinch grip strength

(Figure 16)

Step-by-Step Demonstration Method

1 Place hand dynamometer between participantrsquos thumb and forefinger (lateral pinch grip) as shown in

Figure 16



4 Ask several other audience members of different sizes

(ie weight height) andor gender to perform steps 1ndash

3 and compare their maximum forces this

demonstrates the effects of anthropometry (ie size

variability among people) Encouraging audience

members to compete for the largest force production

often increases participation and friendly competition

Make sure to point out to the audience how much the

forces produced varied across the group

5 Instruct the participants to exert 2 lbs of force to

provide them with a general understanding of what it

feels like to exert that level of force

6 Ask the audience to identify tasks at their worksite

where they use a pinch grip and exert more than 2 lbs

of force Repetitive tasks for which a pinch grip is used

should also be avoided Ask the audience to identify

repetitive tasks at their worksite for which they use a

pinch grip

7 Discuss the possibility of using a better tool or

workstation design to avoid using pinch grips

Grip Types

23

Pinch Grip Strength and Applications Take -Home Messages

Maximum forces

exerted with a pinch

grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)

Figure 16 Example of a pinch grip (lateral) and the resulting maximum force

Grip Types

24

Power Grip Effect of Grip Width

Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether

or not the grip width

necessary to

perform tasks is

appropriate

Supplies

Hand dynamometer that allows grip strength to be evaluated

for multiple grip widths (Figure 17)


NarrowGrip and WideGrip videos

1 Place the hand dynamometer in the participantrsquos hand

and instruct him or her to place the wrist in a neutral

posture (Figure 17)

2 Measure the maximum force the participant can produce

using three to five different grip widths If using only

three different grip widths use grips 1 3 and 5 as shown

in Figure 17

3 Record the force produced for each grip width and

compare these values across the different grip widths

You should notice that for very wide grips and for very

narrow grips the participant will not be able to produce

as much force as with the intermediate grips (Figure 18)


(ie height weight) andor gender to perform steps 1ndash3

and compare their maximum forces the forces produced

will vary showing the effect of anthropometry)

However the maximum force for each participant should

be produced for a grip width of 175 to 375 inches

5 Ask the audience to identify tasks at their worksite where

a power grip is required at or near their minimum or

maximum grip width capacity Determine whether or not

these tasks require workers to exert forces near their

maximum capabilities

6 Discuss with the audience how they may use a better tool

or workstation design to avoid using power grip widths

that are too narrow or too wide

Grip Types

25


Figure 17 The power grip is shown for five different grip widths The narrowest grip is Grip 1 the width increases for each subsequent grip with Grip 5 being the widest grip

Grip Types

26

Power Grip Effect of Grip Width Take -Home Messages

Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)

Figure 18 Maximumndashforce output for each grip width Note that

for this participant Grip 2 had the highest force production

Grip Types

27

SECTION 4 HAND-TOOL SELECTION AND USE

Principles

Select tools that allow neutral postures to be used

Use tools with handles designed for a power grip

Use tools with handles that are appropriately sized and shaped for the userrsquos hand

Use tools with built-in features (eg springs that open tool handles) that minimize forceful exertions required to use the tool

When operating heavy tools ensure they accommodate using both hands to support the tools weight

Hand-tool design can play an important role in the reduction of MSDs A tool that is

designed with consideration for the workerrsquos tasks can greatly reduce the workerrsquos exposure to

risk factors for MSD However using a poorly designed tool or an inappropriate tool negatively

impacts the entire body by dictating the postures assumed by the worker to complete the task

and increasing the resulting forces exerted by the worker Such tools can also directly apply

unwanted forces or vibrations to other body parts

Several factors should be considered when purchasing or selecting a hand tool The topics

discussed in the above sections all play a role in whether or not a hand tool is designed with the

worker or task in mind Some of these points will become clearer after performing the

demonstrations in this section Before performing these demonstrations consider the following

questions related to the safety of the tools you use

Does the orientation of the handle allow the worker to use neutral joint postures Does the size of the handle allow for the midrange of grip (175ndash375 inche s hand in the shape of a ―C) width when using a power grip

Does the handle extend past the palm Is the handle shape contoured to fit the palm If a pinch grip is required is the force the worker must exert lt 2 lbs For heavier tools such as power tools do the features of the tool allow the worker to support the toolrsquos weight with both hands

To obtain a detailed checklist for hand-tool selection refer to the NIOSH publication ―Easy

Ergonomics A Guide to Selecting Non-Powered Hand Tools [NIOSH 2004]

28

Tool-Handle Size and Shape

Objectives

To understand why

handle size is

important when

selecting tools

Supplies

One screwdriver whose handle has a diameter size that

complements the hand and a comfortable appropriate shape

One screwdriver whose handle has a smaller diameter size that

does not complement the hand and does not have a

comfortable appropriate shape

Wood block with screw

Clamp to affix wood block to tabletop


1 Clamp wood block and screw to tabletop

2 Instruct the participant to grasp the appropriately sized

screwdriver that has the larger diameter handle

Instruct the participant to show the audience how

heshe is gripping the screwdriver (Figure 19)

3 Repeat the previous step using the other screwdriver

with a smaller diameter handle that does not

complement the hand Discuss observed differences in

gripping the two screwdrivers

4 Instruct the participant to drive a screw with both

screwdrivers Ask them which one feels more

comfortable in his or her hand and is easier to grasp

when the screw starts to provide resistance The handle

with the larger diameter that complements the hand

should make it easier for the participant to apply torque

to drive the screw

5 Discuss with the audience the fact that selecting a hand

tool with a handle that complements the hand reduces

the effort needed to accomplish the task thus reducing

fatigue and the required muscle activity this in turn

reduces discomfort while using the tool

Hand-Tool Selection and Use

29

Tool-Handle Size and Shape Take -Home Messages

Tools whose handles

are sized and shaped

to complement the

hand require less

effort to use thereby

reducing the muscle

fatigue that leads to

discomfort

Figure 19 Evaluating the effect of tool-handle diameter


30

Tool-Handle Orientation

Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the

tool will be applied

and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies

Screwdriver (battery-powered) with pistol-grip and inline-grip

capabilities (Figure 20)

Wood block with screw in block

Clamp to hold wood block in place while screw is being driven

with screwdriver


1 Clamp the wood block to a tabletop so that the block is

perpendicular to the table and the screw is driven parallel

to the tabletop

2 Place the screwdriver in the inline position and instruct

the participant to begin driving the screw

3 Place the screwdriver in the pistol-grip position and

instruct the participant to begin driving the screw

4 Ask the participant if he or she can feel a difference

between the two techniques Ask the audience which grip

would be best to use for this task (answer pistol grip)


parallel to the table and the screw is driven perpendicular

to the tabletop



7 Place the screwdriver in a pistol-grip position and


8 Ask the participant if he or she feels a difference between

the two techniques Ask the audience which grip would

be best to use for this task (answer could vary depending

on height of participant relative to the tabletop which

affects hisher wrist and shoulder angle)


31


Adjustability in

tools or multiple

tool designs is

important because it

allows for neutral

postures to be

adopted

When selecting or

purchasing a tool

consider the ability

of the toolrsquos handle

to be adjusted in

multiple positions to

keep the wrist in a

neutral posture

Figure 20 Examples of situations in which a pistol grip and inline grip would be useful as a means for keeping the wrist in a

neutral posture

Note This demonstration can be done without actually driving

a screw into a wood block You can ask the participant to

simulate driving a screw into a tabletop and into the wall The

differences in postures can be observed and discussed by the

audience


32

Features to Reduce Forceful Exertions

Objectives

shy

To increase

awareness that some

tools have design

features that reduce

forceful exertions

when the tool is used

to perform a task

Supplies

Spring-loaded needle-nose pliers (Figure 21)

Needle-nose pliers that are not spring loaded (Figure 21)

Portable EMG device with audible sounds to indicate muscle

activity (optional) (Figure 5)


1 If using a portable EMG device place the electrodes on

the forearm a s shown in Figure 5

2 Adjust the output sounds to a range where minimal

sounds are heard when the participant wiggles his or

her fingers

3 Instruct the participant to close and then open the

spring-loaded needle-nose pliers

4 Note the intensity of the sounds from the portable EMG

device


needle-nose pliers that are not spring loaded

6 The intensity of the sounds from the portable EMG

device will be increased when using the nonspring

loaded pliers compared to the spring-loaded pliers

When using pliers for a work activity individuals often

use their dominant hand to both open and close the

pliers Spring-loaded pliers remove the need to open

the pliers and reduces the force requirements on the

hand


between the two tools

Hand Tool Selection and Use

33

Features to Reduce Forceful Exertions Take -Home Messages

Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task

8 Discuss with the audience that even though a tool may

be spring loaded it may be still difficult to use if the

resting-grip width is large (see Section 3 concerning

grip widths)

9 Discuss with the audience other design features that

reduce forceful exertions such as counterbalances

ratcheting tools keyless drill chucks

Figure 21 Two types of pliers one with a spring that reduces forceful exertion when opening the jaw and one without a

spring

NOTE Another example of reduced forceful exertions as a

result of design features is the insertion of a bit into a

screwdriver that requires manual tightening of the chuck with a

key as compared to a screwdriver with a chuck that is simply

pushed down and then released


34

One- and Two-Handed Tools

Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across

both arms instead of

just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in

difficulty controlling

the tool increased

fatigue and poor-

quality

workmanship

Supplies

Electric drill with capability to hold drill with one hand or with

two hands using an additional handle (Figure 22)

Wood block with a screw

Clamp to affix wood block to a table


1 Instruct the participant to hold the drill at waist height

and then at shoulder height with one hand and note the

degree of effort required to hold the drill for both

2 Instruct the participant to grab the additional handle

with the second hand and again hold the drill at waist

and then shoulder height It should be easier with both

hands on the tool because the muscles from both arms

are now being used to hold the drill this reduces the

force produced by each individual muscle

3 Explain to the audience that because force in each

muscle has decreased fatigue will set in later than if

the task was performed with only one hand

4 Clamp down the wood block with the screw

5 Instruct the participant to drive the screw while holding

the drill with only one hand


the drill with both hands

7 Ask the participant if he or she feels more control when

using two hands


35

Features to Reduce Forceful ExertionsTake -Home Messages

Select tools that are

properly sized in

overall dimensions

weight and power

for the specific task

Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features

that allow the tool to

be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control

of the tool and less

fatigue

8 Ask the audience if they perform tasks that should be

performed with a tool that has the one- and two-handed

design feature

8 Discuss the concept relating to the toolrsquos power and the workerrsquos ability to control the toolmdashas the power of the

tool increases a workerrsquos ability to control the tool

decreases this may result in poor-quality workmanship

Also buying tools with excessive power may have

negative consequences for the worker by requiring greater

muscle exertions and causing an earlier onset of fatigue

Figure 22 Example of one-handed and two-handed drilling


36

SECTION 5 FATIGUE FAILURE AND BACK PAIN

Principles

Repeated lifting even at submaximal levels may eventually lead to damage of the spine (fatigue failure)

Substantially reducing loads placed on the spine can greatly minimize the risk of fatigue failure

The spine consists of a column of bones called vertebrae that are separated by flexible discs

(Figure 23)

Figure 23 Image of vertebrae disc and endplates

The discs serve as cushions and allow the spine to assume many postures

Degeneration of these discs is a common source of back pain which is thought to result from a

loss of disc nutrition [Adams et al 2006] Because discs do not have a blood supply they rely

on obtaining their nutrition from the adjacent bones (or vertebrae) Normally nutrients flow

from the vertebrae to the disc through structures called vertebral endplates The endplates are on

the top and bottom of each vertebrate Unfortunately these endplates may fracture if an

excessive force or repeated loads are placed on them by the contracting back muscles as

occurs when lifting [Brinckmann et al 1989]

Researchers believe that endplate fractures usually occur through repeated loading by a

process known as fatigue failure [Bogduk 1997 Brinckmann et al 1988 Adams et al 1995

2006 Gallagher et al 2005 Marras 2008] Fatigue failure begins when a load causes a small

crack in a vertebral endplate Subsequent loads (eg repeated lifting) will cause this crack to

expand leading to a large fracture [Brinckmann et al 1988] The body heals this fracture with

scar tissue but the scar tissue does not allow nutrients to get to the disc causing it to degenerate

[Bogduk 1997] As the disc degenerates fissures and tears in the disc will begin to appear

When these fissures or tears extend to (or occur in) the outer portions of the disc a painful

inflammation may occur Unfortunately because the disc has a decreased blood supply repair

of the tissues is a slow process [Bogduk 1997] At the same time the disc often continues to

become loaded during activities of daily living which may result in additional damage to the

disc even while repairs are ongoing The slow healing combined with continuous loading and

trauma to the tissues is thought to lead to a vicious cycle of chronic pain and inflammation

[Barr and Barbe 2004]

37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and

repetition of manual

lifting tasks

Supplies

One pen cap

One paper clip for each audience member


1 Take intact pen cap and bend ―tail once

2 Show audience members that there is a discoloration at

the spot where the bending occurred which is a visual

example of subfailures occurring

3 Continue to bend the pen cap about five times and then

show the audience that the discoloration has expanded

4 Explain to the audience that if you continue to bend

the pen cap it would eventually fail

5 Explain to the audience that for some materials (eg

paper clip vertebrae) fatigue failure is not visible

6 Distribute one paper clip to each audience member

7 Ask the audience to bend the paper clip back and forth

and count the number of cycles it can withstand before

breaking

8 Ask various audience members how many cycles it

took before the paper clip failed emphasize that the

number of cycles varies for the paper clips as no one

paper clip is exactly the same as another This is also

true for people and their vertebrae Just like with the

paper clips some workerrsquos will experience fractures in

their vertebrae very quickly as others require many

cycles despite undergoing the same loading conditions

9 Show the graph in Figure 24 to the audience

Fatigue Failure and Back Pain

38

Fatigue Failure

10 Explain that every type of material has an ultimate load (ie the load at which it

fails when that load is applied only once) The graph in Figure 24 illustrates the

amount of loads the spine can handle without breaking Because every spine is

unique the ultimate load varies somewhat for each spine Thus the y-axis of this

graph represents the percentage of ultimate load The x-axis represents the

number of cycles a load was applied For example if you applied a load to a

spine that was 80 of its ultimate load you would be able to apply that load

100 times before the spine would fail Likewise if you applied a load that was

only 50 of its ultimate load you could apply that load 1000 times before

failure If you applied a load that was only 30 of its ultimate load you could

complete an infinite number of loading cycles without the spine ever failing

11 Explain to the audience that this means they are not ―doomed to having a back injury Rather if the load applied to the spine is decreased substantially they

could perform their job an infinite number of times and never injure their spine

You may also increase your core strength to better handle loadsmdasha balanced

body in terms of abdominal and back strength makes a more stable core when

trained together

12 Discuss ways to reduce the load applied to the spine such as decreasing the

weight of the object reducing the moment arm (see Section 6) removing

barriers and eliminating twisting and back flexion


39

Fatigue Failure Take -Home Messages

Often the vertebrae

of the back can have

multiple subfailures

that are not visible

but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine

Figure 24 A pen cap that is bent multiple times visually shows fatigue a paper clip shows the result of failure The graph (generalized for bone) illustrates how the same load lifted

many times may ultimately over time lead to failure


40

SECTION 6 MOMENT ARMS AND LIFTING

Principles

Reduce the weight of the object being lifted

Keep loads close to the body when lifting

The best way to prevent low-back pain is to prevent the initial fatigue failure of the vertebral

endplates In general for a given task if the forces exerted by back muscles are high (eg in

heavy lifting) fatigue failure will occur more quickly However if forces produced by the low-

back muscles are decreased the risk of injury also decreases [Brinckmann et al 1988]

Forces produced by the lower back muscles can be reduced by minimizing the weight being

lifted or carried However those forces can also be reduced by minimizing the moment (see

Glossary) or by minimizing the moment arm (ie lever arm) When lifting a n object as shown

in Figure 25 the moment arm is the horizontal distance between the object and the person As

this distance increases the moment (ie torque) involving the workerrsquos back also increases

The muscles of the lower back must produce more force to counteract this moment so that the

person does not fall forward Even li ght objects can cause large forces in the lower back if those

objects are lifted or carried farther away from the body

Weight and moment arm are not the only considerations in determining forces produced by

the lower back muscles Other factors mostly related to the object being lifted should also be

briefly mentioned The size and shape of the object and the handholds on the object affect the

workerrsquos lifting style Also the existence of physical barriers that separate the worker from the

object to be lifted plays a role in the forces exerted in lifting the object because barriers force a

worker to hold an object farther away from his or her body while the worker moves the object

over the barrier A barrier often requires the worker to lift or hold an object incorrectly The

distribution of the weight across the object itself is also a consideration because an awkward

weight distribution can also cause the worker to lift and carry the object incorrectly Detailed

information about these factors can be found in Waters et al [1993] and [NIOSH 1994]

41

Figure 25 These schematics illustrate how increasing the distance between the worker and the object being lifted increases the overall moment (ie torque) for which the back muscles must

compensate by expending more force

42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies

A moment-arm simulator (Figure 26)

Three rectangular blocks of equal weight

Step-by-Step Demonstration Method See Introduction

video

1 Place two of the three blocks on opposite sides of the

fulcrum at equal distance from the fulcrum of the

moment-arm simulator

2 The moment-arm simulator should be perfectly

balanced

3 Move one of the blocks to twice the distance from the

fulcrum

4 Note that the ―see-saw will tip towards the block that

is furthest from the fulcrum This occurs because the

moment arm (ie the distance from fulcrum) is larger

for this block Thus the moment or torque produced

by this block is greater than that of the second block

5 Add a second block to the side of the moment-arm

simulator with the shortest distance from the fulcrum

6 Note that the moment-arm simulator will now balance

again indicating that it is capable of withstanding

twice as much force because the moment arm is half

as long

7 Discuss with the audience the point that the weight of

the object is not the only consideration in producing

forces on the bodymdashas the horizontal distance

increases the resulting moment also increases

Moment Arms and Lifting

43

Moment Arms Take -Home Messages

During manual

material handling

reduce the moment

arm as much as

possible by reducing

the load on the

lower back and

keeping the load

close to the body

Design workstations

and storage facilities

that allow the

worker to keep

objects close to his

or her body when

lifting them

Figure 26 A moment-arm simulator showing that more forceweight (W arrow indicates direction of force) is needed to balance the ldquosee sawrdquo if the moment arm (L) is shorter on one

side of the fulcrum as compared to the other side


44

Moment Arms and the Low Back

Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an

object is not the only

consideration in

determining forces

produced by the

lower back the

position of the

weight of the load in

relation to the body

also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting

forces exerted by the

low-back muscles

Supplies

A moment-arm simulator made from aluminum (Figure 27)

Spring scale

Metal weights


video

1 Place known weights midway between the fulcrum and

the end of the horizontal bench


balanced as the spring scale undergoes loading

3 Note the force in the spring scale

4 Move the weights farther away from the fulcrum

5 Again the moment-arm simulator should be perfectly

balanced however the force in the spring scale should

increase

6 Discuss with the audience that the only change made

was the moment arm indicating that weight is not the

only factor affecting how much force must be exerted

7 Relate the spring scale to the low-back muscles

fulcrum to the vertebrae and weight to an object being

carried

8 Discuss with the audience how the forces exerted by

the low-back muscles must increase as an object is

moved farther away from the pelvis


45


Take -Home Messages

The length of the

moment arm and

weight of the object

both affect the


lower-back muscles

The size and shape

of the object lifted

or carried existence

of barriers and

design of

workstations are all

factors that affect

the moment arm of

an object being

lifted or carried

9 Discuss with the audience the factors that may

increase the moment arm when attempting to

liftcarry objectsmdashsize and shape of the object

existence of a barrier methods used to complete

tasks or design of workstations

Figure 27 Moment-arm simulator with dial scale showing that as the moment arm is increased the resulting force acting on

the scale increases


46

APPENDIX A SUGGESTED SUPPLIES

All supplies needed for the demonstrations are included in the following list Purchasing

information is also provided although most of the supplies can be purchased at hardware 1

stores

1 The National Institute for Occupational Safety and Health does not endorse any manufacturer or supplier of these products When using the

general guidelines provided above it is the responsibility of the end user to assess the products they intend to purchase and use

47

Hand dynamometer (grip type)mdashevaluates grip strength for multiple grip widths (Figure

A-2 A and B)

o This device measures the hand force generated by a power grip (ie where the

user curls the fingers towards the palm) The force generated is displayed on a

dial or on a digital output If attempting to locate this device using an Internet

search engine (eg wwwgooglecom wwwyahoocom wwwaskcom) the

following phrase may be helpful when searching for a vendormdash―hand

dynamometer grip width You may also consider adding the keywords

―adjustable or ―multiple This item costs from $225 to $375 depending on the

manufacturer and the number of grip widths the dynamometer can evaluate

Among common suppliers of dynamometers identified from an internet search

are Baseline Tool Company Medline Industries and Sammons Preston Rolyan

o This device may also be used to evaluate pinch grip by adjusting the width of

the grip to its minimum

Hand dynamometer (pinch type)mdashevaluates pinch grip strength (Figure A-2C)

o This device measures the force generated by a pinch grip (ie where the user

presses the thumb against the index finger) The force generated is displayed on a

dial or on a digital output If attempting to find this device using an Internet


following phrase may be helpful when searching for a vendormdash―dynamometer

pinch grip You may also consider adding the keywords ―strength or ―price

This item costs from $250 to $350 depending on the manufacturer and the

maximum force measured by the device Among common supplier of pinch type

dynamometers identified from an internet search are Dynatronics Baseline

Tool Company and Jamar

Traditional screwdriversmdashvarying handle diameters (Figure A-2D)

o Traditional screwdrivers are designed with a hard plastic handle Many

manufacturers offer screwdrivers with various handle diameters and working-end

size (ie a larger handle diameter corresponds to a larger working-end size)

However other manufacturers attempt to keep the handle diameter as large as

possible Screwdrivers with different handle diameters but similar-sized working

ends should be obtained for the demonstrations These items may be purchased

at any standard hardware store for about $20 each

Screwdrivermdashcan convert to either an inline or pistol grip (Figure A-2 E a nd F)

o Screwdrivers that can be adjusted from an inline to a pistol grip are available at

most standard hardware stores This item costs approximately $50

Electric drillmdashcan be held with both hands when additional support is needed (Figure

A-2 G a nd H)

o Electric drills that have a second handle to allow support from both hands may

be purchased at any hardware store This item costs approximately $100 to $200

Needle-nose pliersmdashwith and without a spring-loaded handle (Figure A-2 I and J)

Needle-nose pliers may be purchased at a hardware store This item may be purchased

for approximately $20

Portable electromyography (EMG) devicemdashbattery-operated device with audible

feedback where the intensity of the sounds produced by the device increases with

increased muscle activity (Figure A-2K)

o When using electrodes placed on the surface of the skin (with tape similar to a

Band-Aid) the amount of muscle activity may be measured when a worker is at

rest and while performing a task The amount of muscle activity experienced by

the worker is conveyed with an audible sound As muscle activity increases so

does the intensity of the sound produced by the device If attempting to locate

this device using an Internet search engine (eg wwwgooglecom

wwwyahoocom wwwaskcom) the following phrase may be helpful when

finding a vendormdash―portable EMG audible This item costs from $300 to $450

depending on the manufacturer For the purpose of this document the ―pocket

ergometer from AliMed was used however NIOSH does not endorse any 1

specific manufacturer However a supply of disposable surface electrodes must

also be purchased These typically come in packs of 50 100 or 1000 A pack of

100 costs about $10 If using an Internet search engine the following phrase may

be helpfulmdash―EMG disposable surface electrode Among the common suppliers

of electrodes identified from an internet search are Nikomed USA Inc and

Biopac Systems Inc

o The product directions should be followed for the specific device purchased In

general the device will likely consist of a small box a cable with three leads at

the end and a package of electrodes The small box houses the signal processing

and output capabilities of the unit Three electrodes should be placed on the skin

above the same muscle or muscle group Once affixed to the skin the leads of

the cable should be connected to the electrodes The cable will likely consist of

two red leads and one black lead The black lead should be connected to the

48

electrode that is midway between the other two (Figure A-2K) The red leads

should be connected to the electrodes on either side Once the device is turned

on the audible output may need to be adjusted based on the amount of activity

associated with the specific muscle or muscle group being evaluated

Standard weights or custom-made blocks (35 in x 5 in x 1 in) ndash four steel blocks

weighing approximately 5 lbs each

o Standard weights may be purchased at any store that sells supplies for weight

training

o Custom steel blocks can be constructed from steel stock purchased at most larger

hardware stores Some also offer the service of cutting these items to size for

their customers Other materials may also be used for this task as long as the

weight and size of all blocks are uniform

Dial scalemdashmust have the ability to attach to objects at either end of the scale (Figure A

2L)

o This item is best purchased using an online source Use an Internet search engine

(eg wwwgooglecom wwwyahoocom wwwaskcom) The following search

phrase may be helpful when finding a vendormdash―hanging spring dial scale This

item may cost from $10 to $50 depending on the manufacturer and the

maximum force that the device measures For these demonstrations a 10-lb

capacity or greater is recommended Among the common suppliers of this

device identified from an internet search are Detecto Global Industrial

Calibex and Salter Brecknell Mechanical Scales

Moment-arm simulator that is 40 in long (20 in from fulcrum to end x 5 in width)mdashmust be

able to support the weight of the four steel blocks (Figures A-1 a nd A-2L)

shy

Figure A-1 Dimensions for the moment-arm simulator

49

o This item may be custom-made Suggested dimensions complement the

dimensions provided above for the steel blocks Additionally this size allows the

device to be viewed by all audience members when training is given in a room

that is the size of a standard classroom The ―see-saw should be able to move

freely about its fulcrum Aluminum stock may be purchased at most larger

hardware stores some stores also offer the service of cutting these items to size

for their customers Alternatively this device may be made from wood at a less

expensive cost Materials other than aluminum may be used Aluminum was

suggested due to its relatively light weight and low cost You should mark the

locations along the see-saw that are 10 inches and 15 inches from the fulcrum as

a visual aid for placing the steel blocks during the demonstrations

o Other similar devices may be purchased for less than $100 An internet search

found that common suppliers included Fisher Scientific

Pen capmdashmust be plastic and easy to bend (Figure A-2M)

o Remove from the top of a pen

Paper clipmdashstandard size (Figure A-2N)

o Metal uncoated paper clips

50

Figure A-2 Examples of the suggested supplies for the demonstrations

51

APPENDIX B USEFUL IMAGES FOR HANDOUTS

52

53

54

55

REFERENCES

Adams MA Bogduk N Burton K Dolan P [2006] The biomechanics of back pain

Edinburgh Scotland Churchill Livingstone p 316

Adams MA Dolan P [1995] Recent advances in lumbar spinal mechanics and their clinical

significance Clin Biomech 103ndash19

Barr AE Barbe MF [(2004] Inflammation reduces physiological tissue tolerance in the

development of work-related musculoskeletal disorders J Electromyogr Kines 1477ndash85

Basmajian JV De Luca CJ [ 1985] Muscles alive their functions revealed by th

electromyography 5 ed Baltimore MD Williams and Wilkins

Bechtol CO [1954] Grip test the use of a dynamometer with adjustable handle spacings J

Bone Joint Surg AM 36A820ndash832

Bogduk N [1997] Clinical anatomy of the lumbar spine and sacrum 3rd ed Edinburgh

Scotland Churchill Livingstone p 252

Brinckmann P Biggemann M Hilweg D [1989] Prediction of the compressive strength of

human lumbar vertebrae Spine 14(6)606ndash610

Brinckmann P Biggemann M Hilweg D [1988] Fatigue fracture of human lumbar

vertebrae Clin Biomech 3(Supplement 1)1ndash23

Chaffin DB Andersson GBJ Martin BJ [2006] Occupational biomechanics 4th ed New

York NY John Wiley amp Sons Inc

Chengalur SN Rodgers SH Bernard TE [2004] Kodakrsquos ergonomic design for people at nd

work 2 ed Hoboken NJ John Wiley amp Sons Inc p 111

Clarke HH [1966] Muscular strength and endurance in man Englewood Cliffs NJ Prentice

Hall

Gallagher S Marras WS Litsky AS Burr D [2005] Torso flexion loads and the fatigue

failure of human lumbosacral motion segments Spine 30(20)2265ndash2273

Jones RH (1974) Unpublished results Eastman Kodak Company No other publication

information available

Kumar S [2004] Muscle strength Boca Raton FL CRC Press LLC p 27

Marras WS [2008] The working back a systems view New York NY John Wiley and

Sons p 310

Martin RB Burr D Sharkey NA [1998] Skeletal tissue mechanics New York NY

Springer-Verlag

NIOSH [2008] Ergonomics and risk factor awareness training for miners By Torma-

Krajewski J Steiner LJ Unger RL Wiehagen WJ Cincinnati OH US Department of Health

and Human Services Public Health Service Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health DHHS (NIOSH) Publication No 2008

111 Information Circular 9497

NIOSH [2004] Easy ergonomics a guide to selecting non-powered hand tools By Hight R

Schultz K Hurley-Wagner F Feletto M Lowe BD Kong YK Waters T Cincinnati OH US

shy

56

Department of Health and Human Services Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health DHHS (NIOSH) Publication No 2004ndash

164

NIOSH [1994] Applications manual for the revised NIOSH lifting equation By Waters TR

Putz-Anderson V Garg A Cincinnati OH US Department of Health and Human Services

Centers for Disease Control and Prevention National Institute for Occupational Safety and

Health DHHS (NIOSH) Publication No 94ndash110

Ozkaya N Nordin M (1999) Fundamentals of biomechanics equilibrium motion and nd

deformation 2 ed New York NY Van Nostrand Reinhold Company

Sanders MS McCormick EF [1993] Human factors in engineering and design New York

NY McGraw-Hill Inc

Silverstein BA Stetson DS Keyserling WM Fine LJ [1997] Work-related musculoskeletal

disorders comparison of data sources for surveillance Am J Ind Med 31(5)600ndash608

Silverstein MA Silverstein BA Franklin GM [1996] Evidence for work-related

musculoskeletal disorders a scientific counterargument J Occup Environ Med 38(5)477ndash484

Waters TR Putz-Anderson V Garg A Fine LJ [1993] Revised NIOSH equation for the

design and evaluation of manual lifting tasks Ergonomics 36(7)749ndash776

57

Delivering on the Nationrsquos promise safety and health at work for all people through research and prevention

To receive NIOSH documents or more information about occupational safety and health topics contact NIOSH at

1ndash800ndashCDCndashINFO (1ndash800ndash232ndash4636) TTY 1ndash888ndash232ndash6348 e-mail cdcinfocdcgov

or visit the NIOSH Web site at wwwcdcgovniosh

For a monthly update on news at NIOSH subscribe to NIOSH eNews by visiting wwwcdcgovniosheNews


tradeSAFER bull HEALTHIER bull PEOPLE

Report of Investigations 9684

Practical Demonstrations of Ergonomic Principles

Susan M Moore PhD Janet Torma-Krajewski PhD CIH CPE

Lisa J Steiner MS CPE

DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for D isease Control and Prevention

National Institute for Occupational Safety and Health Pittsburgh Research Laboratory

Pittsburgh PA

July 2011


Disclaimer









NIOSH at



wwwcdcgovniosheNews


July 2011


ii

CONTENTS


iii

FIGURES















iv

ACKNOWLEDGEMENTS








v

GLOSSARY















energy










involve the palm





vi



required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Disclaimer









NIOSH at



wwwcdcgovniosheNews


July 2011


ii

CONTENTS


iii

FIGURES















iv

ACKNOWLEDGEMENTS








v

GLOSSARY















energy










involve the palm





vi



required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








CONTENTS


iii

FIGURES















iv

ACKNOWLEDGEMENTS








v

GLOSSARY















energy










involve the palm





vi



required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








FIGURES















iv

ACKNOWLEDGEMENTS








v

GLOSSARY















energy










involve the palm





vi



required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








ACKNOWLEDGEMENTS








v

GLOSSARY















energy










involve the palm





vi



required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








GLOSSARY















energy










involve the palm





vi



required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57










required force









vii


















addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57

























addressed


Grip types



























information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57
















information









Suggested Supplies




a reasonable cost





















2
















Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57























Graphics




3


Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Principles
































4









These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57
















These







[Bechtol 1954]

5



6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57










6




7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57











7


Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To understand the


awkward postures

on muscle activity

for the wrist elbow

shoulder and lower

back

Supplies


sound (Figure 5)


audible signals






placement)




posture (Figure 6)





activity)


8

4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








4

5











9







10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57














10





(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57












(Figure 8)









11

















12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57
























12




13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57











13


video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









video



















14


Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Whenever possible

workers should

work in a neutral

posture to reduce

muscle activity and

reduce fatigue













15


Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To increase

awareness of how


production

capabilities and

worker fatigue


require workers to

use awkward

postures while

exerting force

Supplies


Stopwatch


video


shown in Figure 13















this posture









16









the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57
















the wrist occur




17


When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









When body joints

are in awkward

postures maximum

force produced

decreases

Muscle fatigue will

occur earlier when

working in an

awkward posture


posture




18


Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Principles
























19













20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57




















20


Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To increase

awareness that

Maximum force

generated using a

power grip is

greater than when

using a pinch grip

Force production

capabilities differ

among individuals

for both pinch and

power grips

Pinch grips should

be avoided when

possible because it

places high demands

on the hand and

produces less force

than a power grip

Supplies


(Figure 15)


(Figure 15)



PowerGrip videos








15










Grip Types

21


Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Take -Home Messages

A pinch grip should

be used only for


require minimal

forces to be

generated

In general pinch

grips should be

avoided for any

length of time

regardless of the

force required

A power grip should

be used for tasks

that require larger

forces that do not


of precision and

dexterity







Grip Types

22


Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To increase

awareness of

individual maximum

capabilities for a

pinch grip


are performed with

a pinch grip

To understand force

and repetition

requirements of the

task

Supplies


(Figure 16)



Figure 16




















pinch grip



Grip Types

23


Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Maximum forces


grip vary among

workers

A pinch grip should

not be used when

high forces or

repetition are

required

Pinch grips should

be used only for

tasks that require

small forces (lt 2

lbs)


Grip Types

24


Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To increase

awareness of how

grip width affects

maximum strength

for a power grip

To increase

awareness of

individual maximum

capabilities for a

power grip

To discuss whether


necessary to

perform tasks is

appropriate

Supplies







posture (Figure 17)




in Figure 17




















Grip Types

25



Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57










Grip Types

26


Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Maximum force

produced with a

power grip varies

with grip width

Maximum forces

exerted for a power

grip vary among

workers

Tools and

workstations should

be designed so that

workers may use

optimum power grip

widths (175ndash375

inches)



Grip Types

27


Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Principles





















28


Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To understand why

handle size is

important when

selecting tools

Supplies
























to drive the screw







29


Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Tools whose handles


to complement the

hand require less


reducing the muscle


discomfort



30


Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To demonstrate how

tool-handle

adjustability or

orientation may

allow for neutral

postures to be

adopted

To encourage

workers using and

purchasing tools to

consider how the


and whether or not

a different tool or

tool configuration

would be more

appropriate

Supplies





with screwdriver




to the tabletop










to the tabletop











31


Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Adjustability in

tools or multiple

tool designs is


allows for neutral

postures to be

adopted

When selecting or

purchasing a tool



to be adjusted in


keep the wrist in a

neutral posture


neutral posture





audience


32


Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

shy

To increase

awareness that some

tools have design


forceful exertions


to perform a task

Supplies










her fingers




device










hand




33


Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Select tools with


forceful exertions

when preparing the

tool for use and

operating the tool

during the task




grip widths)





spring







34


Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To demonstrate that

muscle activity

decreases when

forces are

distributed across


just one arm

To inform workers

that they should

purchase and use

tools with

appropriate power

because too much

power for the job

may result in


the tool increased

fatigue and poor-

quality

workmanship

Supplies
























using two hands


35



properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57










properly sized in

overall dimensions

weight and power


Too much weight

and power can

increase fatigue in

the worker and

result in poor-

quality

workmanship

When purchasing

heavy power tools

consider features


be held with both

hands

When operating

heavy tools take

advantage of

features that allow

for greater control


fatigue



design feature









36


Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Principles




(Figure 23)
























37

Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








Fatigue Failure

Objectives

To introduce

workers to the

concept of fatigue

failure

To reinforce the

importance of

minimizing object

weight lever

arm barriers and


lifting tasks

Supplies

One pen cap
















breaking











38

Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








Fatigue Failure
















trained together





39


Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Often the vertebrae




but can result in

complete failure

over time

The number of

cycles that lead to

failure of the

vertebrae varies

across the

population

Efforts should be

made to

substantially

decrease loading of

the spine




40


Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Principles

























41



42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57










42

Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








Moment Arms

Objectives

To introduce

workers to the

concept of moments

and moment arms

Supplies




video





balanced


fulcrum











as long






43


During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









During manual

material handling

reduce the moment

arm as much as


the load on the

lower back and

keeping the load

close to the body

Design workstations


that allow the

worker to keep


or her body when

lifting them




44


Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Objectives

To introduce the

effect of moment

arm on forces

exerted by lower

back muscles when

lifting or carrying

an object

To emphasize that

the weight of an


consideration in

determining forces

produced by the

lower back the

position of the



also affects the

forces and stresses

in the low back

To discuss factors

that may increase

the moment arm

and the resulting


low-back muscles

Supplies


Spring scale

Metal weights


video









increase






carried





45


Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









Take -Home Messages

The length of the

moment arm and


both affect the


lower-back muscles

The size and shape



of barriers and

design of


factors that affect

the moment arm of

an object being

lifted or carried







the scale increases


46




stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57











stores



47


A-2 A and B)




































A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57















A-2 G a nd H)
























Biopac Systems Inc








48








training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57















training






2L)











shy


49


















50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57

























50


51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









51


52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57









52

53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








53

54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








54

55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








55

REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57








REFERENCES






















Hall







Sons p 310


Springer-Verlag








shy

56



164








NY McGraw-Hill Inc







57










164








NY McGraw-Hill Inc







57















Documents

Practical Demonstrations of Ergonomic Principles